Impact transducer apparatus

ABSTRACT

An impact transducer apparatus comprises a lever means supported within a housing adapted to pivot between first and second positions. A hammer is attached to the lever means and is adapted to strike a piezoelectric element when the lever means is moved from its first to its second position. A magnetic latch including a magnet member is associated with the lever means for restraining movement of the lever from its first to its second position, and a resilient bias means, having a bent portion, biases the lever means towards its second position. A key reciprocal along an axis is connected to the bias means to increase energy in the bias means so that when the energy in the bias means exceeds a design level associated with the magnetic coupling of the latching means, the latching means releases the lever means and the bias means urges the lever means from its first to its second position, thereby causing the hammer to strike the piezoelectric element.

United States Patent 1191 Sauveur Feb. 12,1974

1 1 lMPACT TRANSDUCER APPARATUS Xavier De Saint Sauveur, Verney Voltaire, France [75] lnventor:

[73] Assignee: Control Data Corporation,

Minneapolis, Minn.

22 Filed: Jan. 8, 1973 211 Appl. No.: 321,873

[52] 11.8. CI 340/365 A, 310/83, 310/87 [51] Int. Cl. H041 15/06 [58] Field of Search 340/365 A: 179/90 K;

[56] References Cited UNITED STATES PATENTS 6/1971 Dorfman 340/365 A 3/1972 Watson 310/83 Primary Examiner-Thomas B. Habecker Attorney, Agent, or Firm-Robert M. Angus; Joseph A. Genovese [57] ABSTRACT An impact transducer apparatus comprises a lever means supported within a housing adapted to pivot between first and second positions. A hammer is attached to the lever means and is adapted to strike a piezoelectric element when the lever means is moved from its first to its second position. A magnetic latch including a magnet member is associated with the lever means for restraining movement of the lever from its first to its second position, and a resilient bias means, having a bent portion, biases the lever means towards its second position. A key reciprocal along an axis is connected to the bias means to increase energy in the bias means so that when the energy in the bias means exceeds a design level associated with the magnetic coupling of the latching means, the latching means releases the lever means and the bias means urges the lever means from its first to its second position, thereby causing the hammer to strike the piezoelectric element.

10 Claims, 6 Drawing Figures PAIENI MBI m4 SHEET 2 BF 2 MAGNE ELEM FILE: 5"

IMPACT TRANSDUCER APPARATUS This invention relates to keyboard apparatus and particularly to keyboard devices capable of generating electric signals upon actuation of a key mechanism.

Alphanumeric keyboard apparatus are useful in association with computer input devices, encoders, and the like. Ordinarily, each key of such keyboard apparatus is associated with a suitable code generating device for generating a unique code upon depression of each key of the keyboard apparatus.

Prior keyboard apparatus have utilized mechanical interconnections to overcome many problems associated with such apparatus. For example, the simultaneous operation of two or more keys by an operator trained for high speed encoding often caused an erroneous code to be established by the encoder. Consequently, mechanical interlocking of the keys was utilized, but this produced a rough, disagreeable touch to the operator. To overcome this problem, some keyboard apparatus utilized key-operable hammers adapted to strike signal generating crystals, such as piezoelectric elements, but-these have not been altogether satisfactory because the hammer often bounced on the crystal, thereby generating an erratic, spurious electric signal. Further, such keyboard apparatus produced a soft touch, not particularly pleasing to the operator.

Further, refinement in the field of keyboard apparatus resulted in the use ofsnap action hammers operable to strike piezoelectric elements to overcome the problem of bouncing hammers as well as to provide a more pleasing touch to the operator. However, such devices have been cumbersome in that they require extensive mechanical apparatus and a considerable amount of space for each such key. A more thorough discussion of such apparatus may be found in copending application of Marcel Brisebarre and Xavier de Saint Sauveur, for Impact Transducer Keyboard Apparatus, Ser. No. 156,146 filed June 21, 1971 and assigned to the same assignee as the present application, now U.S. Pat. No. 3,725,908 granted Apr. 3, 1973.

It is an object of the present invention to provide a signal generating keyboard device which is easily assembled, requires minimal space, and whose operation is pleasing to an operator.

It is another object of the present invention to provide signal generating keyboard apparatus wherein a manually operable key is operable to increase energy stored in a spring, or the like, so that a hammer associated with the spring is biased toward a signal generating device. A magnetic latch restrains the hammer from movement toward the signal generating device until the energy within the spring exceeds a design level, at which point the latch releases permitting the spring to bias the hammer toward the signal generating device to generate a signal.

It is another object of the present invention to provide a key-operable signal generating apparatus having an actuator slidably reciprocal along an axis and which requires a minimal amount of space.

In accordance with the present invention, a keyoperable signal generating apparatus is provided having a manually operable actuator reciprocal along an axis. Bias means is provided so that movement of the actuator along the axis in one direction increases energy the bias means releases and the bias means urges the hammer means to strike the signal generating means thereby generating an electric signal.

One feature of the present invention resides in the provision of a mechanical coupling between the bias means and the actuator to provide snap action to the apparatus.

Another feature of the present invention resides in the provision of a depressable key apparatus which biases a hammer to strike a signal generating means with uniform force.

The above and other features of this invention will be more fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 is a section view of a key-operable signal generating device in accordance with the presently preferred embodiment of the present invention;

FIG. 2 is a section view taken at line 2-2 in FIG. 1;

FIG. 3 is a section view taken at line 3-3 in FIG. 1;

FIG. 4 is an orthogonal view of a portion of the apparatus illustrated in FIG. 1; and

FIGS. 5 and 6 are section views of the apparatus, as in FIG. 1, illustrating the manner of operation.

With reference to the drawings there is illustrated in impact transducer apparatus 10 in accordance with the presently preferred embodiment of the prevent invention. Apparatus 10 includes an outer housing 11 having an axis 12 and an inner chamber 13. Housing 14 is fitted within chamber 13 and is axially positioned within the chamber by suitable stops (not shown) on housings l1 and 14. Housing 14 preferably includes planar surface 15 disposed substantially parallel to axis 12 and an inclined surface 16. Surfaces 15 and 16 join at junction 17 for purposes to be hereinafter explained. Inclined surface 18 protrudes from surface 15 at an angle different from the angle of inclination of surface 16, for purposes to be more fully understood hereinafter. Piezoelectric crystal 19 is supported by housing 14 and preferably flush with surface 16 and is connected via leads 20 and 21 to end contacts 22 and 23, respectively. Magnet 24 is supported by housing 14 and preferably is flush with surface 18. Preferably, and as shown particularly in FIG. 4, housing 14 includes, at each side thereof, a first recessed portion 25 and a second recessed portion 26.

Leaf spring 30 includes first and second arms 31 and 32, respectively, joined at the upper end thereof by a cross arm 33. Lever arm 34, integral with spring 30, extends from the lower end portion 35 of leaf spring 30. Arms 31 and 32 are bent in the region defined by axis 36 so that the upper portion of arms 31 and 32 extend substantially parallel to axis 12, and lever arm 34 extends substantially parallel to the lower portion of arms 31 and 32. The lower end portion 35 of leaf spring 30 is supported at the junction 17 between surfaces 15 and 16 so that the spring may pivot about the axis formed by junction 17. The upper end of lever arm 34 includes a magnetic keeper 38 adapted to be magnetically coupled to magnet 24 and a hammer 37 adapted to strike piezoelectric crystal l9.

Actuator 40 includes a substantial cylindrical portion 41 extending through bore 42 of housing 11. Shoulder 43 on actuator 40 defines an upper stop against upper surface 44 of housing 11. Actuator 40 includes a pair of downwardly depending arms 45 and 46. Guides 47 on housing 11 guide the travel of actuator 40 along axis 12. Actuator 40 further includes a slot 48 which snugly receives the upper end portion 33 of leaf spring 30. Preferably, each arm 45 and 46 includes a shoulder 49 adapted to bear against respective ones of arms 31 and 32 of leaf spring 30. Manually operable key 50 is attached to. the upper end of actuator 40 at cylindrical portion 41.

In operation of the impact transducer apparatus in accordance with the present invention, and particularly with reference to FIGS. 1 and 4-6, manual depression of key 50 causes an axial movement of actuator 40 along axis 12. Axial movement of actuator 40 bends arms 31 and 32 of leaf spring 30 near axis 36, thereby increasing the energy stored within theleaf spring, as shown in FIG. 5. When the energy in leaf spring 30 exceeds a design level, the magnetic coupling between keeper 38 and magnet 24 is overcome by the energy stored within the leaf spring, and the energy within spring 30 causes the spring to pivot about the axis defined by junction 17. When spring 30 pivots aboutjunction 17, lever 34 pivots causing hammer 37 to strike piezoelectric crystal 19, thereby causing the element to generate an electric signal. The signal generated by element 19 is transmitted via leads 20 and 21 to pins 22 and 24 for operation on an electric circuit.

The energy stored in spring 30 upon release of the magnetic coupling causes a uniform striking force to occur against the piezoelectric crystal thereby assuring the generation of a uniform electric pulse upon each actuation of the key. Upon release of the key, spring 30 biases actuator 40 upwardly thereby returning key 50 to its original position, and thereby biasing the lever arm 34 to the position illustrated in FIGS. 1 and 4.

As can be determined from a comparison of FIGS. 1 and 6, surface 18 is disposed at approximately the same angle to axis 12 as the plane of lever arm 34 when the lever arm is in the position shown in FIG. 1. Similarly, surface 16 is disposed at approximately the same angle to axis 12 as the plane of lever arm 34 when the lever arm is in the position shown in FIG. 6. Thus, the inclination of surface 18 is such as to enable magnet keeper 38 to mate against magnet 24 in a contiguous, or flush, fashion, while surface 16 is inclined so that hammer portion 37 strikes piezoelectrid element 19 at substantially a right angle to lever arm 34 to assure maximum impact against the element.

As shown particularly in FIGS. and 6, recessed portion 25 provides an open region for receiving the bent regions of arms 31 and 32 as the spring is compressed, and recessed portion 26 enables axial travel of arms 45 and 46 of actuator 40.

One feature of the invention resides in the fact that the upper cross arm 33 of leaf spring 30 is fixedly attached in slot 48 of actuator 40. This feature prevents pivotal rotation of the upper portion of the leaf spring so that the compressional bending of the leaf spring occurs substantially entirely at the region of axis 36. Further, shoulder 49 on arms 45 and 46 of the actuator prevent the arms 31 and 32 of spring 30 from bending in the wrong manner to further assure concentration of energy at the region of arms 31 and 32 as defined by axis 36. By concentrating the bending action of spring 30 to a region between keeper 38 and pivot region 17, substantially all energy imparted to the spring by axial movement of actuator 40 is transferred to the lever arm 34 to overcome the magnetic coupling between keeper 38 and magnet 24 and to pivotally rotate arm 34 to cause hammer 37 to impact against element 19.

The present invention thus provides a transudcer impact apparatus which is reliable in operation, requires minimal space, is easily assembled and manufactured, and which provides a pleasing touch to the operator. The device is reliable in operation, and provides a uniform electric signal output upon each actuation of the key.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example and not of limitation, but only in accordance with the scope of the appended claims.

I claim:

1. Impact transducer apparatus comprising: a housing; lever means in said housing adapted to pivot between first and second positions; hammer means attached to said lever means; a piezoelectric element mounted to said housing in relationship to said hammer means as to be spaced from said hammer means when said lever means is in its first position and to be struck by said hammer means when said lever means moves from its first to its second position, said piezolectric element being adapted to generate an electric signal upon being struck by said hammer means; latching means associated with said lever means for restraining movement of said lever means from its first to its second position, said latching means including a magnet member magnetically coupling a region of said lever means; resilient bias means biasing said lever means towards its second position, said bias means having a first end pivotally supported in said housing and having a bent region so that a portion of said bias means between said region and said first end is disposed at an angle to an axis; key means supported by said housing and reciprocal along said axis, said key means engaging a second end of said bias means to move said second end axially to increase energy stored in said bias means; whereby when energy stored in said bias means exceeds a design level associated with the magnetic coupling of said latching means, said latching means releases the lever means and said bias means urges said lever means to move from its first to its second position to thereby cause said hammer means to strike said piezoelectric element.

2. Impact transducer apparatus according to claim 1 wherein said bias means comprises a resilient spring means having first and second spaced resilient arms, said lever means being integral with said spring means and extending between said arms at one end thereof, said arms having a bent region at a midpoint along their length so that an upper portion of said arms are disposed substantially parallel to said axis and the lower portions of said arms and the bias means are disposed at an angle to said axis.

3. Impact transducer apparatus according to claim 2 wherein the length of said lever means is greater than the length of the lower portions of said arms.

4. Impact transducer apparatus according to claim 1 wherein said key means comprises a manuallydepressable push button attached to an actuator, said actuator being slidably supported within said housing for reciprocation along said axis, said actuator including securing means securing an upper end of said bias means to restrain the upper end of said bias means from rotation about said axis.

5. Impact transducer apparatus according to claim 4 wherein said bias means comprises a resilient spring means having first and second spaced resilient arms, said lever means being integral with said spring means and extending between said arms at one end thereof, said arms having a bent region at midpoint along their length so that an upper portion of said arms are disposed substantially parallel to said axis and the lower portions of said arms and the lower means are disposed at an angle to said axis.

6. Impact transducer apparatus according to claim 5 wherein said actuator includes depending arm portions adapted to bear against the upper portions of the arms of said spring means to concentrate bending of the arms of said spring means at their respective bent regions.

7. Impact transducer apparatus according to claim 5 wherein said spring means includes a cross arm between its resilient arms at the upper end thereof, and said securing means comprises a slot in said actuator, said cross arm being secured in said slot.

8. Impact transducer apparatus according to claim 7 wherein said actuator includes depending arm portions adapted to bear against the upper portions of the arms of said spring means to concentrate bending of the arms of said spring means at their respective bent regions.

9. Impact transducer apparatus according to claim 6 wherein the length of said lever means is greater than the length of the lower portions of said arms.

10. Impact transducer apparatus according to claim 4 wherein the length of said lever means is greater than the length of the lower portions of said arms. 

1. Impact transducer apparatus comprising: a housing; lever means in said housing adapted to pivot between first and second positions; hammer means attached to said lever means; a piezoelectric element mounted to said housing in relationship to said hammer means as to be spaced from said hammer means when said lever means is in its first position and to be struck by said hammer means when said lever means moves from its first to its second position, said piezolectric element being adapted to generate an electric signal upon being struck by said hammer means; latching means associated with said lever means for restraining movement of said lever means from its first to its second position, said latching means including a magnet member magnetically coupling a region of said lever means; resilient bias means biasing said lever means towards its second position, said bias means having a first end pivotally supported in said housing and having a bent region so that a portion of said bias means between said region and said first end is disposed at an angle to an axis; key means supported by said housing and reciprocal along said axis, said key means engaging a second end of said bias means to move said second end axially to increase energy stored in said bias means; whereby when energy stored in said bias means exceeds a design level associated with the magnetic coupling of said latching means, said latching means releases the lever means and said bias means urges said lever means to move from its first to its second position to thereby cause said hammer means to strike said piezoelectric element.
 2. Impact transducer apparatus according to claim 1 wherein said bias means comprises a resilient spring means having first and second spaced resilient arms, said lever means being integral with said spring means and extending between said arms at one end thereof, said arms having a bent region at a midpoint along their length so that an upper portion of said arms are disposed substantially parallel to said axis and the lower portions of said arms and the bias means are disposed at an angle to said axis.
 3. Impact transducer apparatus according to claim 2 wherein the length of said lever means is greater than the length of the lower portions of said arms.
 4. Impact transducer apparatus according to claim 1 wherein said key means comprises a manually-depressable push button attached to an actuator, said actuator being slidably supported within said housing for reciprocation along said axis, said actuator including securing means securing an upper end of said bias means to restrain the upper end of said bias means from rotation about said axis.
 5. Impact transducer apparatus according to claim 4 wherein said bias means comprises a resilient spring means having first and second spaced resilient arms, said lever means being integral with said spring means and extending between said arms at one end thereof, said arms having a bent region at midpoint along their length so that an upper portion of said arms are disposed substantially parallel to said axis and the lower portions of said arms and the lower means are disposed at an angle to said axis.
 6. Impact transducer apparatus according to claim 5 wherein said actuator includes depending arm portions adapted to bear against the upper portions of the arms of said spring means to concentrate bending of the arms of said sPring means at their respective bent regions.
 7. Impact transducer apparatus according to claim 5 wherein said spring means includes a cross arm between its resilient arms at the upper end thereof, and said securing means comprises a slot in said actuator, said cross arm being secured in said slot.
 8. Impact transducer apparatus according to claim 7 wherein said actuator includes depending arm portions adapted to bear against the upper portions of the arms of said spring means to concentrate bending of the arms of said spring means at their respective bent regions.
 9. Impact transducer apparatus according to claim 6 wherein the length of said lever means is greater than the length of the lower portions of said arms.
 10. Impact transducer apparatus according to claim 4 wherein the length of said lever means is greater than the length of the lower portions of said arms. 